public class Demo10 {
    public static int count = 0;

    public static void main(String[] args) throws InterruptedException {
        Object locker = new Object();

        Thread thread1 = new Thread(() -> {
            for (int i = 0; i < 10000; i++) {
                synchronized(locker) {
                    count++;
                }
            }
        });

        Thread thread2 = new Thread(() -> {
            for (int i = 0; i < 10000; i++) {
                synchronized(locker) {
                    count++;
                }
            }
        });

        thread1.start();
        thread2.start();

        thread1.join();
        thread2.join();

        System.out.println(count);
    }
}
